√(x·√x - x) + √x - x = 0
√x·√(√x - 1) + √x - √x·√x = 0
√x·(√(√x - 1) + 1 - √x) = 0
√x·(√(√x - 1) - (√x - 1)) = 0
√x·(√(√x - 1) - √(√x - 1)·√(√x - 1)) = 0
√x·√(√x - 1)·(1 - √(√x - 1)) = 0
√x = 0 --> x = 0
√(√x - 1) = 0 --> x = 1
1 - √(√x - 1) = 0 --> x = 4